The cancer-testis lncRNA LINC01940 promotes gastric cancer malignant progression and chemoresistance by enhancing ribosome biogenesis via TAF15-mediated NOL11 SUMOylation.

[BACKGROUND] Aberrant ribosome biogenesis promotes gastric cancer (GC) progression and contributes to chemoresistance by sustaining protein synthesis, upon which GC cell survival depends. However, the regulatory role of cancer-testis-associated long noncoding RNAs (CT-lncRNAs) in modulating ribosome biogenesis in GC remains largely unexplored.

[METHODS] First, we performed a screening of lncRNAs and identified CT-lncRNA LINC01940 on the basis of integrated expression and survival analyses using The Cancer Genome Atlas (TCGA) data. Subsequently, the impact of LINC01940 on GC progression and chemosensitivity was evaluated using in vitro cell functional assays, patient-derived organoid models, and in vivo subcutaneous tumor xenograft experiments. To further elucidate the underlying mechanisms, we employed a comprehensive approach combining bioinformatics analyses, RNA sequencing, fluorescence in situ hybridization, translation assays, ribosomal DNA (rDNA) transcription assays, methylated RNA immunoprecipitation, co-immunoprecipitation mass spectrometry, fluorescence multiplex immunohistochemistry, and RNA pull-down mass spectrometry.

[RESULTS] Normally, testis-specific LINC01940 is aberrantly upregulated in GC and associated with poor prognosis. Functional assays demonstrated that LINC01940 promotes GC cell proliferation and invasion and confers resistance to cisplatin. Mechanistically, LINC01940 is stabilized by methyltransferase 16 (METTL16)/ insulin-like growth factor 2 messenger RNA binding protein 3 (IGF2BP3)-mediated N-methyladenosine (mA) modification, which enhances its ability to act as a scaffold promoting the interaction between the small ubiquitin-like modifier 2 (SUMO2) E3 ligase TATA-box binding protein associated factor 15 (TAF15) and Nucleolar protein 11 (NOL11), promoting the SUMOylation of NOL11 and enhancing its protein stability. This, in turn, increases ribosomal DNA transcription and ribosome biogenesis, thereby promoting GC progression and chemoresistance.

[CONCLUSIONS] LINC01940 is a cancer-testis lncRNA that promotes GC progression and cisplatin resistance by enhancing ribosome biogenesis via the METTL16/IGF2BP3-TAF15-NOL11 axis. These findings suggest its potential as a prognostic biomarker and therapeutic target in GC.